But the executive director of the Brain and Mind Research Institute at the University of Sydney, Ian Hickie, said the data was being misrepresented as 2001 had a high number of suicides, creating the appearance of a fall.

He said the data showed the suicide rate in the latter part of the decade had been steady, or even increased. ''The analysis is entirely unhelpful,'' he said.

Professor Hickie said a proper registry with real-time information on suicide was needed.

''The government response needs to be co-ordinated in response to it just in the same way it would to a public health issue like [flu] infection rates … rather than this Pollyanna notion that rates have fallen,'' he said.

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Suicide remains the leading cause of death among people aged 15 to 34, the ABS figures showed. It has defended the time period in its media release, pointing to a long-term fall in rates, particularly among men.

A former chairman of the National Advisory Council on Mental Health and the director of ConNetica consulting, John Mendoza, said the ABS's release was ''spin''.

The release highlighted NSW as the state with the lowest suicide rate, 8.6 deaths per 100,000 people between 2006 and 2010.

Professor Mendoza said it was ''a dishonest representation'' for the ABS not to mention ''well-documented evidence'' that NSW was less reliable at reporting suicides.

''The media release also ignores the fact that NSW has the worst record for reporting suicide deaths in a timely way and that [in] the reporting of open case findings in the period from 2002 to at least 2007, NSW increasingly left 'open' findings,'' he said.

An open finding can be made by a coroner despite evidence such as suicide notes or witness statements. It can occur because of legal issues about intent and sensitivity to families, cultural practices or religious beliefs, the ABS's website says.

The director of social and demographic statistics at the ABS, James Hinkins, said changes to guidelines had enabled staff to include suicide deaths that had been left open, but he was unable to give details on how often that happened.

Cases were examined initially, then at 12 months and 24 months in order to capture any changes to suicide codes.

''The combination of these two things means the coders can, where there's an open case, look for evidence of a suicide,'' he said.

He said he understood the concern that comparing current suicide statistics with those from 2001 could be confusing but that there had been a real drop in suicide rates since the late 1990s.

''If we look at the males between the age of 15 and 34, there have been quite steady declines in the suicide rate over the 10-year period,'' he said.